ANN ARBOR—Although election rhetoric is heating up and cries of fake news still abound, the University of Michigan Center for Social Media Responsibility finds a continued decline in questionable content on Facebook and Twitter.

The center's Iffy Quotient measures the percentage of the most popular news URLs on a platform that are from "iffy" sites—ones that frequently publish unreliable information. For Facebook, questionable content dropped to 7.2% on July 1 from 12.2% on October 1, 2018, when the center first started reporting the metric. For Twitter, it fell slightly from 11.1% to 10.9%.

The specific cause of the decline remains an open question, says Paul Resnick, director of the Center for Social Media Responsibility.

"Are Facebook and Twitter policing content better? Has the public gotten better at not sharing iffy content? Either way, it's gratifying to see that, at least on this metric, the information ecosystem has improved over the past nine months," Resnick said.

The center is also changing the way it calculates the Iffy Quotient, making the metric more transparent and comparable over time. It has formed a new partnership with NewsGuard, which now serves as the primary source for vetting and rating news and information sites.

The NewsGuard News Website Reliability Index provides a way to differentiate between generally reliable and generally unreliable sites. This index acts as a resource to allow researchers and others to track information reliability on social media, search, messaging and other digital platforms.

NewsGuard rates each site based on nine binary, apolitical criteria of journalistic practice, including whether a site repeatedly publishes false content, whether it regularly corrects or clarifies errors, and whether it avoids deceptive headlines.

It awards weighted points for each criterion and sums them up; a score of less than 60 earns a "red" rating, while 60 and above earns a "green" rating, which indicates it is generally reliable. NewsGuard also identifies which sites are satire—for example, the popular publication The Onion.

For the purposes of calculating U-M's Iffy Quotient, a site with a NewsGuard "red" rating that is not identified as satire is considered iffy.

"We are delighted to provide the NewsGuard News Website Reliability Index to U-M researchers for their important work," said Sarah Brandt, NewsGuard's vice president for News Literacy Outreach. "We make our index product available to researchers and regulators as well as to social media, search and messaging companies so that they have an independent, industrywide benchmark, based on transparent criteria, to use when tracking information reliability online."

"We are very grateful to NewsGuard for providing us with access to their carefully researched ratings of sites," Resnick said. "We also appreciate their broad coverage of sites and look forward to their continued expansion of that coverage."

NewsGuard rates all the news and information websites that account for 96% of online engagement in the U.S. and also operates in the U.K., Germany, France and Italy. Its rapid-response SWAT team also rates new websites with news stories that are trending online, including on social media, so that news consumers can quickly know if a website is generally reliable or not.

Details of how the Iffy Quotient is calculated are included in a report, available online at umsi.info/iffy-quotient-whitepaper. The graph showing trends in the Iffy Quotient for Facebook and Twitter, updated daily, is available at csmr.umich.edu/platform-health-metrics.